JP4608966B2 - Method for manufacturing light emitting device - Google Patents

Description

The present invention relates to a manufacturing how the light-emitting device.

  A light-emitting device using a semiconductor element as a light-emitting element emits light with a small color, high power efficiency, and vivid colors. In addition, a light emitting element which is a semiconductor element does not have a concern about a broken ball. Further, it has excellent initial driving characteristics and is strong against vibration and repeated on / off lighting. Because of such excellent characteristics, light-emitting devices using semiconductor light-emitting elements such as light-emitting diodes (LEDs) and laser diodes (LDs) are used as various light sources.

  In particular, a high-luminance blue light-emitting LED using a GaN-based compound semiconductor has been developed, and a white light-emitting device has been realized by utilizing the luminance. In this white light emitting device, a light emitting element that emits blue light is covered with a resin containing a fluorescent material that emits yellow green light to obtain white light.

  As a means for manufacturing such a light emitting device, it is necessary to coat the light emitting element with a wavelength conversion member. As a method for forming a film of a wavelength conversion member on a light emitting element, there is a method using a potting means or a screen printing means (see, for example, Patent Document 1). FIG. 11 is a schematic process cross-sectional view showing a conventional film forming method using potting means, and FIG. 12 is a schematic process cross-sectional view showing a conventional film forming method using screen printing. These will be described below.

  A light-emitting device 300 using the potting means shown in FIG. 11 has a flip-chip light-emitting element 310 mounted face-down in a cavity 311 having a predetermined shape. The top and side surfaces of the light emitting element 310 are covered with a film 312 containing a fluorescent material 316. The light emitting element 310 is electrically connected to the lead electrode 315. The lead electrode 315 is integrally formed with the cavity 311. In the light emitting device 300, the light emitting element 310 is mounted face-down on the lead electrode 315 in advance. Resin 313 is introduced from the thin tube 314 onto the upper surface of the light emitting element 310. When the protruded resin 313 covers the upper surface and side surfaces of the light emitting element 310 almost completely, the charging is stopped and the resin 313 is cured. In this manner, the film 312 is formed on the upper surface and the side surface of the light emitting element 310.

On the other hand, a light emitting device 400 using screen printing shown in FIGS. 12A and 12B has a flip-chip light emitting element 410 mounted face-down on the upper surface of a substrate 411. The upper surface and side surfaces of the light emitting element 410 are covered with a film 412 containing a fluorescent material 417. The light emitting element 410 is electrically connected to a lead electrode 415 provided on the substrate 411. In the light emitting device 400, as shown in FIG. 12A, a metal mask 416 having a predetermined shape is provided, and a resin 413 is extended with a spatula 414 to form a coating 412 on the upper surface of the light emitting element 410. After the coating 412 is formed, the metal mask 416 is removed as shown in FIG. 12B, and the coating 412 is formed on the upper surface and side surfaces of the light emitting element 410.
JP 2002-134792 A

  However, in the manufacturing method of the light emitting device using the above potting means, there is a problem that the resin 313 does not enter the gap portion between the light emitting element 310 mounted face down and the cavity 311 so that a gap is generated. Since the resin 313 is cured in a state where the gap is generated, the light emitting device 300 is obtained in which a gap remains in the gap portion between the light emitting element 310 and the cavity 311. When the light emitting device 300 is driven, the light emitting element 310 generates heat as it is driven, and this heat is transmitted to the gap to cause thermal expansion, which may lead to damage of the light emitting device 300. In addition, since there is a gap, transmission of heat generated in the light emitting element 310 is deteriorated, and there is a problem that heat radiation of the light emitting element 310 is not sufficiently performed. Furthermore, there is a problem that it is difficult to control the sedimentation and dispersion of the fluorescent material 316 contained in the resin 313.

  On the other hand, also in the method for manufacturing the light emitting device 400 using the screen printing unit, the resin 413 for screen printing does not enter the gap portion between the light emitting element 410 and the substrate 411 mounted face down, so that a gap is generated. In order to fill this gap, a work process for filling the gap is required, and there is a problem that the manufacturing time becomes long.

  Furthermore, in a method for manufacturing a light emitting device using potting or screen printing, a resin layer having a uniform thickness cannot be formed around the light emitting element due to uneven potting or printing, and as a result, the output light also has uneven color. There was also a problem that good output light could not be obtained.

  The present applicant first developed a method for reducing the pressure in the space covered with the covering member and the pedestal and allowing the resin to enter the gap portion other than the portion where the light emitting element and the lead electrode are electrically connected. (Japanese Patent Application No. 2004-076687). According to this method, the resin is filled in the gap between the light emitting element and the pedestal, which has conventionally been difficult to fill with resin, and air is removed from this portion to improve the quality and reliability of the light emitting device. Can do. However, this method requires a step of reducing the pressure in the space covered with the covering member and the pedestal and allowing the resin to enter the gap, so that equipment and processes for pressure reduction are essential, which increases the number of manufacturing steps and labor. There was a problem that it was expensive and costly. For this reason, there has been a demand for a method for manufacturing a light-emitting device that can control the film thickness with a simpler method and accurately.

The present invention has been made to further solve such problems. The main purpose of the present invention is to provide a manufacturing how the light-emitting device an air layer from being formed, and uniformly enhanced orientation characteristics resin was then coated contains a fluorescent material around the light emitting element .

  In order to achieve the above object, a method for manufacturing a light-emitting device according to the present invention is a method for manufacturing a light-emitting device including a light-emitting element and a fluorescent material that converts a part of light emitted from the light-emitting element to a different wavelength. In this method, a light emitting element is mounted on a pedestal having a lead electrode, the lead electrode and the light emitting element are electrically connected, and a curable composition made of a thermosetting resin containing a fluorescent material is emitted. Supplying from the upper surface of the element to the periphery, covering the supplied curable composition with a mold made of a thermoplastic resin, and uniformly coating the light emitting element with the curable composition by the load of the mold; And heating at a temperature equal to or higher than the melting point of the thermoplastic resin constituting the mold, and removing the mold deformed by heating from the light emitting element. Thus, a curable composition such as a thermosetting resin is retained in a molding die composed of a thermoplastic resin, and the curable composition is cured by heating while the molding die is melted, and the periphery of the light emitting element. A uniform curable composition can be formed. In particular, if the method is based on molding, the accuracy of the molding die can be increased, and the film thickness of the curable composition, which has been difficult in the past, can be controlled more accurately.

  In another method of manufacturing a light-emitting device of the present invention, the heating step is heated at a first temperature for curing the curable composition and then at a second temperature for melting the mold. Performed in two steps. Thereby, hardening of a curable composition and melting of a shaping | molding die can be performed reliably at the temperature suitable for each, and a curable composition can be coat | covered more precisely around a light emitting element.

  Furthermore, in another method for producing a light-emitting device of the present invention, the curable composition is adjusted to have a viscosity that impregnates a gap portion where the lead electrode is connected between the light-emitting element and the pedestal. This ensures that the curable composition is filled between the light-emitting element and the pedestal to eliminate the formation of an air layer, prevent breakage due to thermal expansion at this interface, improve heat conduction, and improve heat dissipation. it can.

  Furthermore, in another method for producing a light-emitting device of the present invention, the molding surface of the molding die facing the light-emitting element is molded into a concave shape corresponding to the molding thickness of the curable composition. Thereby, the curable composition supplied to the periphery of the light emitting element can be molded in a state of being held by the mold, and the curable composition can be uniformly formed to a predetermined thickness.

  Furthermore, in another method for manufacturing a light emitting device of the present invention, a molding surface of the molding die facing the light emitting element is molded into a curved shape. As a result, it becomes possible to form a curved surface, which is impossible with conventional resin application using a squeegee or the like, and it is possible to increase the light extraction efficiency by forming the curable composition into a lens shape around the light emitting element.

  Furthermore, in another method for producing a light-emitting device of the present invention, the thermoplastic resin constituting the mold is a resin having releasability from the curable composition. Thereby, when removing a shaping | molding die, a possibility that a curable composition may peel can be reduced and the yield and reliability of a light-emitting device can be improved.

  Furthermore, in another method for manufacturing a light emitting device of the present invention, the thermoplastic resin constituting the mold is an acrylic or methacrylic acid resin.

  Furthermore, in another method for producing a light-emitting device of the present invention, the curable composition is a silicone resin.

According to the manufacturing how the light-emitting device of the present invention, can be reliably filled with the curable composition and the wavelength converting member such as resin between the light emitting element and the base exclusion of air, and prevents the occurrence of voids A high-quality light-emitting element can be obtained. This is because producing how the light-emitting apparatus of the present invention, using a mold made of a thermoplastic resin retains a curable composition and the wavelength conversion member. If the curable composition or the wavelength conversion member is held between the mold and the light emitting element, a resin having a low viscosity can be used, so that the generation of bubbles can be suppressed and the gap between the light emitting element and the pedestal is also suppressed. Resin etc. can be surely infiltrated. In addition, since it is easy to increase the accuracy of the mold when molding, the thickness of the resin or the like can be accurately controlled. As a result, a curable composition or wavelength having a uniform thickness around the light emitting element. By covering the conversion member, a high-quality light emitting device with extremely high accuracy can be obtained. Further, by eliminating bubbles, the adhesiveness and thermal conductivity are improved, and the lifetime of the element can be improved. As described above, according to the present invention, an extremely high-quality light-emitting element can be obtained at a low cost by a simple configuration in which a thermosetting resin curable composition or a wavelength conversion member is molded with a thermoplastic resin mold. The excellent feature that can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments shown below are intended to illustrate the preparation how the light emitting device for embodying the technical idea of the present invention, the present invention is specific to the following manufacturing how the light emitting device do not do. Further, the present specification by no means specifies the members shown in the claims to the members of the embodiments. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the embodiments are not intended to limit the scope of the present invention unless otherwise specified, but are merely described. It's just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and symbol indicate the same or the same members, and detailed description thereof will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing.
(Light emitting device)

FIG. 1 is a schematic cross-sectional view of a light emitting device 100 according to an embodiment. The light-emitting device 100 shown in this figure includes a light-emitting element 110 mounted on the upper surface of a pedestal 101 having lead electrodes 102, a fluorescent-containing resin 120 that covers the periphery of the light-emitting element, and fluorescent light contained in the fluorescent-containing resin 120. A substance 140 is provided. The light emitting element 110 is a flip chip type and has an electrode 113 on a surface connected to the base 101. The pedestal 101 has a lead electrode 102 having a predetermined conductive pattern. One end of the lead electrode 102 is disposed so as to be electrically connected to the external electrode, and the other end of the lead electrode 102 is disposed so as to be electrically connected to the electrode 113 of the light emitting element 110. The electrode 113 of the light emitting element 110 and the lead electrode 102 are electrically connected via a bump or the like. In addition, the periphery of the light emitting element 110 is covered with a fluorescent-containing resin 120 containing the fluorescent substance 140 so that the fluorescent substance 140 is disposed around the light emitting element 110. The fluorescent-containing resin 120 is formed substantially uniformly around the light-emitting element 110, and is filled in a portion other than the connection portion even in the gap between the light-emitting element 110 and the base 101. The fluorescent-containing resin 120 has a role of releasing heat generated in the light-emitting element 110 to the outside through the pedestal 101 and the like. Hereinafter, each member will be described in detail.
(Light emitting element 110)

  2 to 3 show a light emitting device according to an embodiment of the present invention. 2 is a plan view of the light-emitting element, and FIG. 3 is a cross-sectional view taken along line III-III ′ of FIG. The light emitting element 110 includes a material such as a GaN-based material, an AlGaN-based material, an InGaN-based material, an InAlGaN-based material, BN, or SiC, and can emit light from an ultraviolet region to a visible light region. In particular, it is preferable to use a light emitting element having a light emission peak wavelength in the vicinity of 350 nm to 550 nm and to have a light emitting layer capable of emitting light having a light emission wavelength capable of efficiently exciting the fluorescent material 140. Here, a nitride semiconductor light emitting element will be described as an example of the light emitting element 110, but is not limited thereto. As shown in FIG. 3, the nitride semiconductor light emitting device according to the present embodiment includes a semiconductor layer 112 formed by sequentially laminating an n-type layer, an active layer, and a p-type layer made of a nitride semiconductor on a sapphire substrate 111. The n-side electrode is formed on the n-type semiconductors that are separated from each other and exposed in a line shape, and the p-side electrode includes a p-ohmic electrode and a plurality of p-ohmic electrodes formed on the p-ohmic electrode. A p-pad electrode is used.

  More specifically, in the nitride semiconductor light emitting device, in the stacked body including the n-type layer, the active layer, and the p-type layer, as shown in FIG. 2A, a part of the p-type layer and the active layer are formed in a line shape. By removing the plurality of grooves, the n-type semiconductor layer 114 is exposed in a line shape. Furthermore, n pad electrodes 115 are formed on the exposed n-type semiconductor layer 114 as shown in FIG. On the other hand, the p-side electrode is composed of a translucent p-ohmic electrode formed on almost the entire surface of the p-type semiconductor layer 116 and a plurality of p-pad electrodes 117 formed on the p-ohmic electrode.

  The nitride semiconductor light emitting device having the above-described electrode configuration improves the light emission efficiency by injecting a current into the entire light emitting region for the following reasons, and has a relatively large area (for example, 1000 μm × 1000 μm). Also in the nitride semiconductor light emitting device, uniform light emission is possible over the entire light emitting surface.

The light-emitting element 110 has a structure in which an n-type semiconductor layer and a p-type semiconductor layer containing gallium nitride as main components are stacked on a light-transmitting substrate such as a sapphire substrate or a silicon substrate, and is formed in each semiconductor layer. The n pad electrode 115 and the p pad electrode 117 thus formed are electrically connected to the lead electrode 102 provided on the base 101 through bumps. The gap portion other than the portion where the light emitting element and the lead electrode 102 are electrically connected does not contain air, and in order to prevent short circuit between the p pad electrode 115 and the n pad electrode 117, Resin 120 is inserted. The bonding between the pad electrodes 115 and 117 and the lead electrode 102 is performed by ultrasonic bonding of solder, gold bumps between the conductive pattern and the pad electrode, conductive paste such as gold, silver, palladium, rhodium or the like. A conductive paste or the like can be used.
(Pedestal 101)

  The pedestal 101 mounts the light emitting element 110 and is electrically connected thereto. A lead electrode 102 having a predetermined shape is formed on the pedestal 101. The lead electrode 102 has a connected portion that is electrically connected to the light emitting element 110 and a portion that is electrically connected to the external electrode. From the viewpoint of preventing corrosion, it is preferable that only these two parts are exposed on the pedestal 101, but parts other than both parts may be exposed in order to improve the light reflection efficiency. The pedestal 101 is provided with a lead electrode 102 at a position where it is electrically connected to the light emitting element 110 and facing the n pad electrode 115 and the p pad electrode 117 of the light emitting element 110. On the other hand, the part electrically connected to the external electrode is connected by wire bonding using a wire. As a result, the light emitting element 110 is electrically connected to the external electrode via the lead electrode 102. The pedestal 101 is formed of a glass epoxy laminated substrate, a liquid crystal polymer substrate, a polyimide resin substrate, a ceramic substrate, or the like.

  The lead electrode 102 can also have a predetermined conductive pattern. For the conductive pattern, a good electrical conductor such as copper, phosphor bronze, iron or nickel can be used. Furthermore, noble metal plating such as silver, gold, palladium, and rhodium can be applied to the surface of the conductive pattern. Further, as means for electrically connecting the light emitting element 110 and the lead electrode 102, means via the bump 103 can be used.

Although not shown, the light emitting element can be mounted on the submount substrate instead of being directly mounted on the pedestal, and can be mounted on the pedestal via the submount substrate. Further, the pedestal can be a submount substrate. When the pedestal is a submount substrate, a lead electrode not covered with a fluorescent-containing resin can be used as an external terminal. Alternatively, the pedestal itself may be a mounting substrate. Furthermore, the light emitting element can adopt a face-up structure in addition to a face-down structure. Furthermore, the lead electrode of the base and the light emitting element can be electrically connected by wire bonding.
(Fluorescent resin)

  The fluorescence-containing resin 120 constitutes a wavelength conversion layer in which the fluorescent material 140 is mixed as a wavelength conversion member. In addition, the thermosetting resin before hardening is equivalent to the curable composition in a claim. The fluorescent material 140 is preferably mixed in the fluorescent-containing resin 120 at a substantially uniform ratio. However, it can also mix | blend so that a fluorescent material may be unevenly distributed. For example, the fluorescent material 140 is unevenly distributed on the outer surface side of the fluorescent-containing resin 120 and separated from the contact surface between the light-emitting element 110 and the fluorescent-containing resin 120, so that the heat generated in the light-emitting element 110 is converted into the fluorescent material 140. The deterioration of the fluorescent material 140 can be suppressed by making it difficult to transmit to the light source. The fluorescent-containing resin 120 is preferably a silicone resin composition, a modified silicone resin composition, or the like, but an insulating resin composition having translucency such as an epoxy resin composition, a modified epoxy resin composition, or an acrylic resin composition. Things can also be used. In addition, a pigment, a diffusing agent, and the like can be mixed in the fluorescent-containing resin 120.

  The fluorescent-containing resin 120 is preferably soft even after being cured. Before curing, the fluorescence-containing resin 120 is spread around the light-emitting element 110, and the fluorescence-containing resin 120 is infiltrated into a gap portion other than the portion where the light-emitting element 110 and the lead electrode 102 are electrically connected. A liquid having a low viscosity is preferred. In conventional resin application methods by screen printing, it is necessary to use a resin with high viscosity because shape retention using a certain degree of viscosity is required. Therefore, the fluidity is low and the gap between the light emitting element and the pedestal is used. If it becomes difficult to enter and voids occur, or if the viscosity is high, bubbles may easily enter the resin and an air layer may be formed during sealing, which causes light loss and color unevenness at the interface. In addition, there is a problem that the air layer thermally expands due to heat generation of the light emitting element and causes breakage. In order to prevent this and to allow the resin having a low viscosity to enter the gap, it was necessary to eliminate bubbles using a defoaming machine or the like, which required the number of processes and cost. On the other hand, since this embodiment performs mold forming, it can be reliably formed into a desired shape even when a resin having a low viscosity is used. In the underfill process of filling the gap between the light emitting element 110 and the pedestal 101 with resin, the resin can surely enter without defoaming, and the formation of an air layer can be prevented.

  It is preferable that the fluorescent-containing resin 120 has adhesiveness. By providing the fluorescence-containing resin 120 with adhesiveness, the adhesion between the light emitting element 110 and the pedestal 101 can be enhanced. The adhesiveness includes not only those exhibiting adhesiveness at room temperature but also those that are bonded to the fluorescent resin 120 by applying predetermined heat and pressure. In addition, the fluorescent resin 120 can be applied with temperature or pressure or dried to increase the fixing strength.

  The film thickness of the fluorescent resin 120 is determined by the gap between the mold 130 and the light emitting element 110. The molding surface of the molding die 130 is molded according to the size and shape of the light emitting element 110 covered with the fluorescent-containing resin 120. Preferably, the film thickness of the fluorescent-containing resin 120 is about 10 μm to 150 μm, more preferably about 25 μm to 100 μm, and still more preferably about 75 μm. By molding, it becomes easy to uniformly form the fluorescent-containing resin 120 having a desired thickness. In particular, since the accuracy of the mold 130 is relatively high, more accurate film thickness control can be realized. By setting the upper surface and side surfaces of the light emitting element 110 to a predetermined thickness, the directivity can be improved. However, the film thickness is not particularly limited, and a very thin film or a thick film can be used.

Moreover, it is preferable to use a thermosetting resin for the fluorescence-containing resin 120. The heating temperature is appropriately changed depending on the curing temperature of the fluorescence-containing resin 120, but is preferably 70 ° C or higher and 130 ° C or lower. This is because it is necessary to cure the fluorescence-containing resin 120 at a temperature equal to or lower than the service temperature of the light emitting element 110.
(Mold 130)

  The fluorescent-containing resin 120 is molded by covering the molding die 130 in an uncured state. The mold 130 is made of a thermoplastic resin. As a result, the wavelength conversion layer can be formed by melting the mold 130 while curing the fluorescence-containing resin 120 that is a thermosetting resin by heating. Further, the thermoplastic resin of the mold 130 is made of a resin having releasability from the fluorescence-containing resin, thereby avoiding the peeling of the fluorescence-containing resin when the mold 130 is removed, and improving the manufacturing yield. The reliability of the light emitting device is also improved. As the thermoplastic resin, for example, an acrylic acid-based or methacrylic acid-based resin can be used. The molding die 130 can be molded into a predetermined shape by a casting method, an extrusion molding method, a pressing method, or the like.

  The molding die 130 has a molding surface formed on the inner surface facing the light emitting element. The molding surface is molded into a concave shape corresponding to the molding thickness of the fluorescent-containing resin. The concave vertical and horizontal sizes are made larger than the vertical and horizontal dimensions of the light emitting element 110. The concave inner height is set higher than the height to the upper surface of the light emitting element 110 mounted on the pedestal 101. By setting the distance between the upper surface of the light emitting element 110 and the inner side of the concave molding surface and the distance between the vertical and horizontal sides of the light emitting element 110 and the inner side of the concave molding surface to be substantially equal distances, A uniform fluorescent-containing resin 120 can be formed. If a wavelength conversion layer containing a wavelength conversion member that converts the wavelength of light emitted from the light emitting element 110 is uniformly formed, the fluorescent material contained in the fluorescent resin 120 and positioned between the concave shaped surface and the light emitting element 110 140, the wavelength of light emitted from the upper and side surfaces of the light emitting device 110 can be uniformly wavelength-converted or transmitted, and the mixed color of the wavelength-converted light and the emitted color from the light emitting device is emitted without color unevenness. In addition, high-quality light emission excellent in color mixing properties and orientation characteristics can be realized. However, the distance between the upper surface of the light emitting element 110 and the inner side of the molding surface, and the distance between the vertical and horizontal directions of the light emitting element 110 and the inner side of the molding surface can also be changed. The amount of light can be adjusted by changing the amount of the fluorescent material 140 according to the amount of light from the upper surface and the amount of light from the side surface of the light emitting element 110. In addition, by arranging the light emitting element 110 at substantially the center of the mold 130 having a cup shape, the thickness of the fluorescent resin 120 can be made uniform vertically and horizontally.

In addition, the mold 130 can be formed not only in a concave shape having a substantially uniform thickness, but also in a curved surface such as a dome shape or a lens shape. By using a dome shape or a lens shape, the light condensing property can be improved in the manufactured light emitting device. For example, the molding surface can be a curved surface so that the upper surface of the fluorescent-containing resin 120 is formed in a lens shape, thereby improving the light collection efficiency from the light emitting device and improving the light extraction efficiency. In particular, the conventional screen printing method is formed on a flat surface for leveling with a squeegee and the like, and it is difficult to form a curved surface. An excellent feature that the fluorescent-containing resin 120 can be molded not only into a shape but also into a desired shape is realized. In addition, in this method, it is not necessary to perform die cutting after resin curing as in normal die molding, and the mold can be removed by melting the molding die 130. Therefore, the degree of freedom is not limited to the molding surface considering die cutting. High resin molding can be realized.
(Fluorescent substance)

  The fluorescent material 140 is a wavelength conversion member that absorbs light from the light emitting element 110 and converts the light into light of different wavelengths. For example, nitride phosphors / oxynitride phosphors mainly activated by lanthanoid elements such as Eu and Ce, lanthanoid phosphors such as Eu, and alkalis mainly activated by transition metal elements such as Mn Earth halogen apatite phosphor, alkaline earth metal borate halogen phosphor, alkaline earth metal aluminate phosphor, alkaline earth silicate, alkaline earth sulfide, alkaline earth thiogallate, alkaline earth silicon nitride At least selected from organic and organic complexes mainly activated by rare earth aluminates, rare earth silicates, or lanthanoid elements such as Eu, which are mainly activated by lanthanoid elements such as germanate or Ce Any one or more are preferable. As specific examples, the following phosphors can be used, but are not limited thereto.

A nitride phosphor mainly activated by a lanthanoid element such as Eu or Ce is M ₂ Si ₅ N ₈ : Eu (M is at least one selected from Sr, Ca, Ba, Mg, Zn). There is.) In addition to M ₂ Si ₅ N ₈ : Eu, MSi ₇ N ₁₀ : Eu, M _1.8 Si ₅ O _0.2 N ₈ : Eu, M _0.9 Si ₇ O _0.1 N ₁₀ : Eu ( M is at least one selected from Sr, Ca, Ba, Mg, and Zn. On the other hand, an oxynitride phosphor mainly activated by a lanthanoid element such as Eu or Ce is MSi ₂ O ₂ N ₂ : Eu (M is at least one selected from Sr, Ca, Ba, Mg, and Zn). More than seeds).

In addition, alkaline earth halogen apatite phosphors mainly activated by lanthanoid-based elements such as Eu and transition metal-based elements such as Mn include M ₅ (PO ₄ ) ₃ X: R (M is Sr, Ca, Ba). X is at least one selected from F, Cl, Br and I. R is any one of Eu, Mn, Eu and Mn. Etc.)

Further, the alkaline earth metal borate phosphor has M ₂ B ₅ O ₉ X: R (M is at least one selected from Sr, Ca, Ba, Mg, Zn. X is F, And at least one selected from Cl, Br, and I. R is Eu, Mn, or any one of Eu and Mn.).

Alkaline earth metal aluminate phosphors include SrAl ₂ O ₄ : R, Sr ₄ Al ₁₄ O ₂₅ : R, CaAl ₂ O ₄ : R, BaMg ₂ Al ₁₆ O ₂₇ : R, BaMg ₂ Al ₁₆ O ₁₂ : R, BaMgAl ₁₀ O ₁₇ : R (R is Eu, Mn, or any one of Eu and Mn).

Examples of alkaline earth sulfide phosphors include La ₂ O ₂ S: Eu, Y ₂ O ₂ S: Eu, and Gd ₂ O ₂ S: Eu.

Examples of rare earth aluminate phosphors mainly activated with lanthanoid elements such as Ce include Y ₃ Al ₅ O ₁₂ : Ce, (Y _0.8 Gd _0.2 ) ₃ Al ₅ O ₁₂ : Ce, Y ₃ There are YAG phosphors represented by the composition formula of (Al _0.8 Ga _0.2 ) ₅ O ₁₂ : Ce, (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ .

Other phosphors include ZnS: Eu, Zn ₂ GeO ₄ : Mn, MGa ₂ S ₄ : Eu (M is at least one selected from Sr, Ca, Ba, Mg, Zn. X is And at least one selected from F, Cl, Br, and I.).

  The phosphor described above contains at least one selected from Tb, Cu, Ag, Au, Cr, Nd, Dy, Co, Ni, Ti instead of Eu or in addition to Eu as desired. You can also.

  Moreover, it is fluorescent substance other than the said fluorescent substance, Comprising: The fluorescent substance which has the same performance and effect can also be used.

  These fluorescent materials can use phosphors having emission spectra in yellow, red, green, and blue by the excitation light of the light emitting element 110, and can also be used in yellow, green, blue green, orange, etc., which are intermediate colors thereof. A phosphor having an emission spectrum can also be used. By using these phosphors in various combinations, light emitting devices having various emission colors can be manufactured.

For example, using a GaN-based compound semiconductor that emits blue light, a Y ₃ Al ₅ O ₁₂ : Ce or (Y _0.8 Gd _0.2 ) ₃ Al ₅ O ₁₂ : Ce fluorescent material is irradiated to convert the wavelength. Do. A light-emitting device that emits white light with a mixed color of light from the light-emitting element 110 and light from the fluorescent material 140 can be provided.

Alternatively, CaSi ₂ O ₂ N ₂ : Eu, which emits light from green to yellow, or SrSi ₂ O ₂ N ₂ : Eu, and (Sr, Ca) ₅ (PO ₄ ) ₃ Cl: Eu, which emits blue light as a phosphor. By using the fluorescent material 140 that contains (Ca, Sr) ₂ Si ₅ N ₈ : Eu that emits red light, a light emitting device that emits white light with good color rendering can be provided. This uses the three primary colors of red, blue, and green, so the desired white light can be achieved simply by changing the blend ratio of the first phosphor and the second phosphor. Can do.

  The particle size of the fluorescent material 140 is preferably in the range of 1 μm to 20 μm, more preferably 2 μm to 8 μm, and particularly preferably in the range of 5 μm to 8 μm. A phosphor having a particle size smaller than 2 μm tends to form an aggregate. On the other hand, a phosphor having a particle size range of 5 μm to 8 μm has high light absorptivity and conversion efficiency. In this manner, the mass productivity of the light-emitting device is improved by including a phosphor having a large particle diameter and having optically excellent characteristics.

Here, the particle size refers to the average particle size obtained by the air permeation method. Specifically, in an environment with an air temperature of 25 ° C. and a humidity of 70%, a sample of 1 cm ³ is weighed and packed in a special tubular container, and then a constant pressure of dry air is flowed to read the specific surface area from the differential pressure. It is a value converted into an average particle diameter. The average particle size of the phosphor used in the present invention is preferably in the range of 2 μm to 8 μm, and it is preferable that the phosphor having this average particle size value is contained frequently. Further, the particle size distribution is preferably distributed in a narrow range, and it is particularly preferable that the number of fine particles having a particle size of 2 μm or less is small. In this way, by using a phosphor having a small variation in particle size and particle size distribution, color unevenness is further suppressed and a light emitting device having a good color tone can be obtained.
(Diffusion agent)

  Further, in addition to the fluorescent material 140, a diffusing agent may be included in the fluorescent-containing resin 120 and the mold 130. As a specific diffusing agent, barium titanate, titanium oxide, aluminum oxide, silicon oxide or the like is preferably used. As a result, a light emitting device having good directivity can be obtained.

Here, in this specification, the diffusing agent refers to those having a center particle diameter of 1 nm or more and less than 5 μm. A diffusing agent having a size of 1 μm or more and less than 5 μm can be suitably used because it can diffuse irregularly the light from the light emitting element 110 and the fluorescent material 140 and suppress color unevenness that tends to occur by using a fluorescent material having a large particle size. it can. In addition, the half width of the emission spectrum can be narrowed, and a light emitting device with high color purity can be obtained. On the other hand, a diffusing agent having a wavelength of 1 nm or more and less than 1 μm has a low interference effect with respect to the light wavelength from the light emitting element 110, but has high transparency and can increase the resin viscosity without reducing the light intensity.
(Filler)

Furthermore, the fluorescent-containing resin 120 and the mold 130 may contain a filler in addition to the fluorescent substance. As a specific material, the same material as the diffusing agent can be used. However, the diffusing agent and the filler have different center particle sizes. In this specification, the center particle size of the filler is preferably 5 μm or more and 100 μm or less. When the filler having such a particle size is contained in the translucent resin, the chromaticity variation of the light emitting device is improved by the light scattering action, and the thermal shock resistance of the translucent resin can be enhanced. As a result, a highly reliable light-emitting device that can prevent disconnection of the wire that electrically connects the light-emitting element and the external electrode or peeling of the bottom surface of the light-emitting element and the bottom surface of the recess of the package even when used at high temperatures. And can. Furthermore, the fluidity of the resin can be adjusted to be constant for a long time, and a sealing member can be formed in a desired place, enabling mass production with a high yield.
(Mounting the light emitting element 110 on the base)

Next, based on FIGS. 4-8, the manufacturing process of the light-emitting device 100 which concerns on Example 1 of this invention is demonstrated. First, as shown in FIG. 4, the flip chip type light emitting element 110 is mounted on a pedestal. Here, the light emitting element 110 is electrically connected to the pedestal lead electrode 102 via a bump. The lead electrode 102 has a predetermined orientation pattern, and is wired on the upper surface or inside of the pedestal 101. The lead electrode 102 is preferably formed with an alignment pattern so as to face the electrode 113 of the light emitting element 110. One end of the lead electrode 102 is exposed from the upper surface or the lower surface of the base 101 and is formed so as to be electrically connected to the external electrode. The other end of the lead electrode 102 is exposed at a portion where the light emitting element 110 is placed. A bump 103 is formed on the other end of the lead electrode 102. The bump 103 is conductive and can be made of a softer material than the lead electrode 102 and the electrode 113, such as solder. The light emitting element 110 is mounted on the upper surface of the lead electrode 102 using ultrasonic vibration means or the like. Accordingly, the electrode 113 of the light emitting element 110 and the lead electrode 102 are electrically connected via the bump 103. The upper surface of the substrate surface of the light emitting element 110 is preferably arranged so as to be substantially parallel to the pedestal 101. This is to prevent the fluorescence-containing resin 120 from flowing out when potting the fluorescence-containing resin 120 in the next step, and to maintain the orientation chromaticity of the light emitting device 100 in a predetermined state.
(Application of fluorescent-containing resin)

Next, a fluorescent-containing resin in which a fluorescent substance is uniformly contained in advance is prepared, and this fluorescent-containing resin is supplied from above the light emitting element as shown in FIG. The fluorescence-containing resin is in a paste form and is adjusted to have a viscosity that can enter the gap between the light emitting element and the pedestal. Further, in order to ensure the penetration of the fluorescence-containing resin into the gap, the fluorescence-containing resin can be filled in a reduced pressure or vacuum state. As means for placing the fluorescent-containing resin 120 on the upper surface of the light emitting element 110, potting means, spraying means, and the like can be used. The amount on which the fluorescent-containing resin 120 is placed is equal to or slightly larger than the volume surrounded by the base 101 facing the light emitting element 110 and the mold 130. By mixing the fluorescent material 140 with the fluorescent-containing resin 120 almost uniformly in advance, it is possible to prevent uneven color of light emitted from the light emitting device 100. In addition to the fluorescent material 140, a diffusing agent, a filler, or the like can be uniformly mixed with the fluorescent-containing resin 120 as necessary. Further, the viscosity of the fluorescent-containing resin 120 may be adjusted so that the fluorescent-containing resin 120 is held on the upper surface of the light-emitting element 110 due to the surface tension and does not flow out. .
(Coating of mold 130)

  Further, as shown in FIG. 6, the fluorescent-containing resin 120 is spread around the light-emitting element 110 by covering the light-emitting element 110 with a molding die 130 from above while the fluorescent-containing resin is applied around the light-emitting element. Note that the phosphor-containing resin can be spread around the light-emitting element by casting the light-emitting element side flip-chip mounted on the submount to face the mold in which the phosphor-containing resin is injected. According to this forming method, the mold can be moved downward, the mold can be heated and contracted, and the residue can be dropped and removed.

The mold 130 is molded in advance by mold molding or the like. The mold accuracy at this time can be manufactured with high accuracy such as a tolerance of ± 2 μm. The mold 130 is molded from a thermoplastic resin. In capping the mold 130 over the phosphor-containing resin, as shown in FIG. 7, the light emitting element 110 is accommodated on the molding surface of the mold 130, and the distance between the molding surface and the light emitting element 110 is constant. That is, the light emitting element 110 is positioned so as to be arranged at the center of the formation surface. For example, the molding die 130 is positioned at a correct position and covered with a positioning guide or a fitting portion. In this example, the fluorescent-containing resin 120 is applied with a uniform film thickness around the light emitting element 110 having a substantially rectangular parallelepiped shape, and the rectangular parallelepiped shape having substantially the same shape is formed to have a size that is slightly larger. The shape of the back surface of the molding die 130 is not particularly limited, and in the example of FIGS. 6 and 7, it is a dome shape, but may be a rectangular parallelepiped shape corresponding to the molding surface. The mold 130 is slowly lowered from the upper surface of the light emitting element 110 on which the fluorescent resin 120 is placed. By slowly covering the mold 130, scattering of the fluorescent resin 120 can be prevented, and the outflow rate of the fluorescent resin 120 can be controlled to some extent. Further, if air bubbles remain between the fluorescent-containing resin 120 and the mold 130, the light extraction efficiency decreases and color variations occur, so that no air remains in the molding surface of the mold 130. Cover. As shown in FIG. 7, the molding die 130 is lowered so that the lower end of the molding die 130 matches the pedestal 101 without a gap. Further, a check valve-like structure, for example, a hem portion of the molding die 130, which is a contact portion between the molding die 130 and the pedestal 101, is projected outward so that air does not enter from the outside into the gap between the light emitting element 110 and the pedestal 101. It is good also as a structure to keep. Further, the application process of the fluorescent-containing resin and the coating process of the mold 130 may be performed almost simultaneously. Thereby, the fluorescence-containing resin 120 can enter the gap portion, and the fluorescence-containing resin 120 can be arranged in the mold 130.
(Curing of fluorescent resin)

  Then, by heating from the state shown in FIG. 7, the fluorescent-containing resin 120, which is a thermosetting resin, is thermoset, and the mold 130 is melted. This step is preferably performed in two stages. First, the fluorescence-containing resin 120 is cured at a first temperature. The first temperature and the heating time are set to a temperature and a time at which the fluorescence-containing resin 120 can be cured according to the type of the thermosetting resin to be used and the coating amount. For example, when the fluorescent resin is a silicone resin, it is cured by heating at about 100 ° C. for about 1 hour. As a result, it was confirmed that a uniform phosphor layer of 75 μm was formed around the die in the silicone resin layer containing the fluorescent substance from the molding accuracy of the thermoplastic resin.

  By curing the fluorescence-containing resin 120, the mold 130 and the fluorescence-containing resin 120, the fluorescence-containing resin 120 and the light emitting element 110, the fluorescence-containing resin 120 and the pedestal 101, and the like can be bonded. And the fluorescent substance 140 contained in the fluorescent-containing resin 120 can be held in a uniformly mixed state. However, after the light emitting element is covered with a mold, it is allowed to stand for several seconds to several hours, and the fluorescent-containing resin can be cured in a state where the fluorescent substance is settled. Accordingly, a portion where the fluorescent substance is densely formed can be formed in the fluorescent-containing resin, so that the light directly emitted from the light emitting element can be reduced and the color unevenness can be reduced. It is also possible to use the fluorescent-containing resin without curing it.

The fluorescent resin 120 is cured by inserting the base 101 covered with the mold 130 into a predetermined heating device and heating it. Further, the base 101 covered with the mold 130 is sealed in a laminate or a bag, immersed in a solution such as water, and the solution is heated while the pressure is applied to the mold 130 and the fluorescent-containing resin 120. Can also be cured. In addition, after coat | covering a light emitting element with fluorescence containing resin, it can stand still for several seconds to several hours before heating, and it can heat and thermoset in the state which the fluorescent substance settled. As a result, it is possible to form a dense portion of the fluorescent substance in the fluorescent resin, and it is possible to expect an effect of reducing color unevenness by reducing light directly emitted from the light emitting element without wavelength conversion. In this specification, the term “curing” includes not only complete curing but also curing in a gel form.
(Melting mold 130)

  Further, the temperature is raised to the second temperature to melt the mold 130. The second temperature is preferably equal to or higher than the temperature at which the fluorescent-containing resin 120 is cured. The second temperature and the heating time are also set to a temperature and time sufficient to melt the mold 130 to the extent that the fluorescent resin 120 is exposed, depending on the type and amount of the thermoplastic resin used. For example, when the mold 130 is a methacrylic acid resin, the temperature is raised to about 170 ° C. to about 200 ° C., and is heated and melted for about 1 hour. As a result, when the methacrylic acid resin reached the melting point, it began to melt with shrinkage. As a result, as shown in FIG. 8, a methacrylic acid resin debris 130Z remained on the upper surface of the fluorescent resin. In this way, the mold 130 is released while the fluorescent-containing resin is molded according to the molding surface of the mold 130. The debris 130Z of the heat-shrinkable mold 130 is removed by scraping or suctioning with a squeegee. By making the mold 130 a resin having good releasability from the fluorescent-containing resin 120, the debris can be removed from the fluorescent-containing resin without damaging the fluorescent-containing resin 120 or causing separation at the interface with the light emitting element 110 during removal. Can be easily separated from

  Note that the mold can be cured simultaneously with the curing of the fluorescent resin. In addition, an adhesive can be applied to the contact portion between the mold and the pedestal, and the adhesive can be cured simultaneously with the curing of the fluorescent resin. Thereby, the adhesive strength of a shaping | molding die and a base can be improved. This adhesive is preferably applied when the mold is placed on the fluorescent-containing resin.

Through the above steps, a light emitting device in which the fluorescent-containing resin is molded with a uniform film thickness around the light emitting element as shown in FIG. 1 is obtained. In particular, the fluorescent-containing resin 120 is coated in an integral state without an interface on the upper surface and side surfaces of the light emitting element 110 and the gap portion other than the portion where the light emitting element 110 and the lead electrode 102 are electrically connected. be able to. As a result, separation at the interface does not occur, and the light extraction efficiency is improved, which is extremely effective. Further, by making the film thickness of the fluorescent-containing resin 120 constant, light emitted from the light emitting element 110 passes through the fluorescent-containing resin 120 having a substantially uniform film thickness, so that a predetermined emission color is realized with good reproducibility. Thus, a light emitting device with little color variation can be realized. In addition, even when the mounting position of the light emitting element mounted on the pedestal 101 is slightly shifted, the effect of reducing the color tone variation can be expected because the thickness of the portion where the fluorescent material is mixed is uniform.
(Method for Manufacturing Light-Emitting Device According to Example 2)

  In the above-described embodiments, the fluorescent-containing resin is applied while maintaining a shape substantially the same as that of the light-emitting element to form a substantially rectangular parallelepiped shape. The containing resin can also be molded. As a method for manufacturing a light emitting device according to Example 2 of the present invention, an example in which a fluorescent-containing resin is molded into a lens shape will be described with reference to FIGS. First, as in FIGS. 4 to 5 of the first embodiment, the light emitting element 210 is mounted on the pedestal 201, and the fluorescent resin 220 is dropped on the upper surface. Then, as shown in FIG. 9, a molding die 230 having a curved molding surface is placed on the fluorescent resin 220. The mold 230 molds the fluorescent-containing resin 220 into a lens shape with the molding surface as the R surface. The inner diameter and curvature radius of the R surface are designed according to the light emitting element 210 to be used and the size of the lens surface formed on the light emitting element 210. In the example of FIG. 9, the outer shape of the light emitting element 210 and the molding die 230 is the same as that of the example of FIG. 6 and the like, and only the molding surface is changed from a concave shape formed by a flat surface to a curved concave shape. The curved concave shape can be easily dealt with by changing the mold for molding the mold 230. Thus, it is difficult to form a curved surface on the molding surface by screen printing using a conventional squeegee or the like, which is a great advantage. In particular, by forming the fluorescent-containing resin 220 in a lens shape, light directed toward the side can be collected and the directivity can be improved, which is suitable as the light emitting device 200. In this manner, with the mold 230 covered on the fluorescent-containing resin 220, it is heated in two steps in the same manner as in Example 1 above, and the thermosetting resin is cured and contracted to be removed, as shown in FIG. The light emitting device 200 can be obtained.

  Further, in the above configuration, only one layer of the fluorescent-containing resin is coated on the light-emitting element, but the resin layer may have a multilayer configuration. At this time, when the fluorescent material is contained in each resin layer, the fluorescent material mixed in each resin layer may be the same or different. For example, by making the fluorescent material mixed in the first resin into a type having an emission peak wavelength on the longer wavelength side than the fluorescent material mixed in the second resin, the fluorescent material in the first resin The wavelength-converted light can be emitted to the outside without being wavelength-converted by the fluorescent material in the second resin, and the wavelength conversion efficiency of the light-emitting device can be improved. Alternatively, a wavelength conversion layer in which a fluorescent material is contained only in a specific layer, such as a resin layer in contact with a light-emitting element, in a multilayer resin layer, and the other layers are light-transmitting resin layers that do not contain a fluorescent material As an alternative, a filler or a diffusing agent may be mixed.

Producing how the light-emitting device of the present invention, the illumination light source, LED Deisupurei, backlight source, traffic signal, can be suitably used in the illuminated switch, various sensors and various indicators, and the like.

It is a schematic sectional drawing which shows the light-emitting device which concerns on one embodiment of this invention. It is a top view of the light emitting element concerning one embodiment of the present invention. It is sectional drawing in the III-III 'line | wire of FIG. It is a schematic sectional drawing which shows 1 process of the manufacturing method of the light-emitting device which concerns on Example 1 of this invention. It is a schematic sectional drawing which shows 1 process of the manufacturing method of the light-emitting device which concerns on Example 1 of this invention. It is a schematic sectional drawing which shows 1 process of the manufacturing method of the light-emitting device which concerns on Example 1 of this invention. It is a schematic sectional drawing which shows 1 process of the manufacturing method of the light-emitting device which concerns on Example 1 of this invention. It is a schematic sectional drawing which shows 1 process of the manufacturing method of the light-emitting device which concerns on Example 1 of this invention. It is a schematic sectional drawing which shows 1 process of the manufacturing method of the light-emitting device which concerns on Example 2 of this invention. It is a schematic sectional drawing which shows 1 process of the manufacturing method of the light-emitting device which concerns on Example 2 of this invention. It is sectional drawing which shows the conventional film formation method using a potting means. It is sectional drawing which shows the conventional film formation method using a screen printing means.

Explanation of symbols

100, 200, 300, 400 ... light emitting device 101, 201 ... pedestal 102 ... lead electrode; 103 ... bump 110, 210, 310, 410 ... light emitting element 111, 411 ... substrate 112 ... semiconductor layer; 113 ... electrode 114 ... n-type Semiconductor layer; 115 ... n pad electrode 116 ... p-type semiconductor layer; 117 ... p pad electrode 120, 220 ... fluorescent resin 130, 230 ... mold; 130Z ... debris 140 ... fluorescent material 311 ... cavity; 312 ... coating; ... resin; 314 ... capillary 315 ... lead electrode; 316 ... fluorescent material; 412 ... coating; 413 ... resin 414 ... spatula; 415 ... lead electrode; 416 ... metal mask;

Claims (8)

A method for manufacturing a light emitting device comprising: a light emitting element; and a fluorescent material that converts a part of light emitted from the light emitting element to a different wavelength,
Mounting a light emitting element on a pedestal having a lead electrode, and electrically connecting the lead electrode and the light emitting element;
Supplying a curable composition comprising a thermosetting resin containing a fluorescent material from the top surface to the periphery of the light emitting device;
Covering the supplied curable composition with a mold made of a thermoplastic resin, and uniformly coating the light emitting element with the curable composition by the load of the mold;
Heating at a temperature equal to or higher than the melting point of the thermoplastic resin constituting the mold;
Removing the mold deformed by heating from the light emitting element;
A method for manufacturing a light-emitting device, comprising: A method of manufacturing a light emitting device according to claim 1,
The heating step is performed in two stages, a step of heating at a first temperature for curing the curable composition and a step of heating at a second temperature for melting the mold. A method for manufacturing a light emitting device. A method for manufacturing a light emitting device according to claim 1 or 2,
The method for producing a light-emitting device, wherein the curable composition is adjusted to have a viscosity that impregnates a gap portion where the lead electrode is connected between the light-emitting element and the pedestal. The light-emitting device according to claim 1,
A method of manufacturing a light emitting device, wherein a molding surface of the molding die facing a light emitting element is molded into a concave shape corresponding to a molding thickness of the curable composition. The light-emitting device according to claim 1,
A method of manufacturing a light emitting device, wherein a molding surface of the molding die facing a light emitting element is molded into a curved surface. The light emitting device according to any one of claims 1 to 5,
A method for manufacturing a light-emitting device, wherein the thermoplastic resin constituting the mold is a resin having releasability from the curable composition. The light-emitting device according to claim 1,
A method for manufacturing a light-emitting device, wherein the thermoplastic resin constituting the mold is an acrylic or methacrylic acid resin. The light-emitting device according to claim 1,
The method for producing a light-emitting device, wherein the curable composition is a silicone resin.

Images